TY - JOUR
T1 - Enhanced expression and release of C-type natriuretic peptide in freshwater eels
AU - Takei, Yoshio
AU - Inoue, Koji
AU - Ando, Kenji
AU - Ihara, Tsuyoshi
AU - Katafuchi, Takeshi
AU - Kashiwagi, Masahide
AU - Hirose, Shigehisa
PY - 2001
Y1 - 2001
N2 - C-type natriuretic peptide (CNP) is recognized as a paracrine factor acting locally in the brain and periphery. To assess the role of CNP in teleost fish, a cDNA encoding a CNP precursor was initially cloned from the eel brain. CNP message subsequently detected by ribonuclease protection assay, using the cDNA as probe, was most abundant in the brain followed by liver, gut, gills, and heart. Expression was generally higher in freshwater (FW) than in seawater (SW) eels, but not in the brain. Plasma CNP concentration measured by a newly developed homologous radioimmunoassay for eel CNP was higher in FW than in SW eels. The CNP concentration was also higher in the heart of FW eels but not in the brain. These results show that CNP is abundantly synthesized in peripheral tissues of FW eels and secreted constitutively into the circulation. Therefore, CNP is a circulating hormone as well as a paracrine factor in eels. Together with our previous demonstration that CNP-specific receptor expression is enhanced in FW eels, it appears that CNP is a hormone important for FW adaptation. Because atrial NP (ANP) promotes SW adaptation in eels, CNP and ANP, despite high sequence identity, appear to have opposite effects on environmental adaptation of the euryhaline fish.
AB - C-type natriuretic peptide (CNP) is recognized as a paracrine factor acting locally in the brain and periphery. To assess the role of CNP in teleost fish, a cDNA encoding a CNP precursor was initially cloned from the eel brain. CNP message subsequently detected by ribonuclease protection assay, using the cDNA as probe, was most abundant in the brain followed by liver, gut, gills, and heart. Expression was generally higher in freshwater (FW) than in seawater (SW) eels, but not in the brain. Plasma CNP concentration measured by a newly developed homologous radioimmunoassay for eel CNP was higher in FW than in SW eels. The CNP concentration was also higher in the heart of FW eels but not in the brain. These results show that CNP is abundantly synthesized in peripheral tissues of FW eels and secreted constitutively into the circulation. Therefore, CNP is a circulating hormone as well as a paracrine factor in eels. Together with our previous demonstration that CNP-specific receptor expression is enhanced in FW eels, it appears that CNP is a hormone important for FW adaptation. Because atrial NP (ANP) promotes SW adaptation in eels, CNP and ANP, despite high sequence identity, appear to have opposite effects on environmental adaptation of the euryhaline fish.
KW - Natriuretic peptide family
KW - Osmoregulation
KW - Radioimmunoassay of eel CNP
KW - Tissue distribution of CNP mRNA
KW - cDNA cloning of eel CNP
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U2 - 10.1152/ajpregu.2001.280.6.r1727
DO - 10.1152/ajpregu.2001.280.6.r1727
M3 - Article
C2 - 11353677
AN - SCOPUS:0034967540
SN - 0363-6119
VL - 280
SP - R1727-R1735
JO - American Journal of Physiology - Regulatory Integrative and Comparative Physiology
JF - American Journal of Physiology - Regulatory Integrative and Comparative Physiology
IS - 6 49-6
ER -